check_disk: Fail on missing arguments for --warning and --critical and fix a test case (#1935)

* check_disk: Fail on missing arguments for --warning and --critical
* Add new test function for percentage expressions and use it in check_disk
* Add error abort in tests if they fail to parse output
* Fix typo in test which probably broke the test since forever :-(

1 files changed, 1 insertions, 0 deletions

diff --git a/plugins/utils.h b/plugins/utils.h
index 62e489b..f939e33 100644
--- a/plugins/utils.h
+++ b/plugins/utils.h
@@ -49,6 +49,7 @@ bool is_positive (char *);
 bool is_negative (char *);
 bool is_nonnegative (char *);
 bool is_percentage (char *);
+bool is_percentage_expression (const char[]);
 
 bool is_option (char *);